Field of the Invention
This invention relates to a yeast strain exhibiting high power to produce alcohol by fermentation of beet molasses as raw material, for example, and to a method for production of fermentation alcohol by the use of the yeast strain.
Prior Art Statement
Cane molasses has found utility in numerous applications such as, for example, the provision of raw material for production of alcohol by fermentation and the culture of bakers' yeast.
In contrast, beet molasses which remains after separation of sucrose from beet is usable only as an additive to animal feed and has virtually no other utility.
One conceivable way of expanding the uses for beet molasses is to use it for the production of spirits by the fermenting it into alcohol. The inventors screened yeasts in search of yeast strains which are suitable for such fermentation. As a result, they have found that the two yeast strains, i.e. a flocculent yeast strain NRIB No. 180 (serial number assigned by National Research Institute of Brewing, Tax Administration Agency of Japan) and a killer yeast strain No. 909-1 (serial number assigned by Tax Administration Agency of Japan), belonging to genus Saccharomyces cerevisiae exhibit a highly desirable fermentability to produce alcohol from beet molasses by fermentation.
In commercial production of alcohol by fermentation using a yeast strain, since the process of fermentation is usually carried out in an open condition, there is an undeniable possibility that some wild yeast will find its way into the fermentation tank and do harm. The yeast used for the fermentation, therefore, is required to possess killer phenotype against invading other harmful wild yeasts. Further, since the yeast is used repeatedly, it is required to possess also a flocculent property to be effectively separated from the fermentation mash. The two yeast strains mentioned above have only one or the other of the two properties, namely killer phenotype or the flocculent property. Neither of these yeast strains, therefore, is capable of efficiently effecting production of alcohol on a commercial scale.